FN6548 Rev 6.00 Page 1 of 26 November 22, 2013 FN6548 Rev 6.00 November 22, 2013 ISL28006 Micropower, Rail to Rail Input Current Sense Amplifier with Voltage Output DATASHEET The ISL28006 is a micropower, uni-directional high-side and low-side current sense amplifier featuring a proprietary rail-to-rail input current sensing amplifier. The ISL28006 is ideal for high-side current sense applications where the sense voltage is usually much higher than the amplifier supply voltage. The device can be used to sense voltages as high as 28V when operating from a supply voltage as low as 2.7V. The micropower ISL28006 consumes only 50μA of supply current when operating from a 2.7V to 28V supply. The ISL28006 features a common-mode input voltage range from 0V to 28V. The proprietary architecture extends the input voltage sensing range down to 0V, making it an excellent choice for low-side ground sensing applications. The benefit of this architecture is that a high degree of total output accuracy is maintained over the entire 0V to 28V common mode input voltage range. The ISL28006 is available in fixed (100V/V, 50V/V, 20V/V and Adjustable) gains in the space saving 5 Ld SOT-23 package and the 6 Ld SOT-23 package for the adjustable gain part. The parts operate over the extended temperature range from -40°C to +125°C. Features • Low Power Consumption. . . . . . . . . . . . . . . . . . . . . . 50μA, Typ • Supply Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.7V to 28V • Wide Common Mode Input . . . . . . . . . . . . . . . . . . . . 0V to 28V • Gain Versions - ISL28006-100 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100V/V - ISL28006-50 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50V/V - ISL28006-20 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20V/V - ISL28006-ADJ . . . . . . . . . . . . . . . . ADJ (Min Gain = 20V/V) • Operating Temperature Range . . . . . . . . . . . . -40°C to +125°C • Packages. . . . . . . . . . . . . . . . . . . . . . 5 Ld SOT-23, 6 Ld SOT-23 Applications • Power Management/Monitors • Power Distribution and Safety • DC/DC, AC/DC Converters • Battery Management/Charging • Automotive Power Distribution Related Literature • See AN1532 for “ISL28006 Evaluation Board User’s Guide” FIGURE 1. TYPICAL APPLICATION FIGURE 2. GAIN ACCURACY vs V RS+ = 0V TO 28V ISL28006 GND ISL28006 ISL28006 +5VDC +12VDC + - +1.0VDC +1.0VDC SENSE SENSE SENSE OUTPUT +5VDC OUTPUT +12VDC OUTPUT MULTIPLE OUTPUT POWER SUPPLY I SENSE +12VDC I SENSE +5VDC I SENSE +1.0VDC + - + - R SENSE +5VDC +5VDC +5VDC R SENSE R SENSE 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 ACCURACY (%) -1.4 -1.2 -1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 V RS+ (V) +100°C +25°C -40°C +125°C GAIN 100
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FN6548Rev 6.00
November 22, 2013
ISL28006Micropower, Rail to Rail Input Current Sense Amplifier with Voltage Output
DATASHEET
The ISL28006 is a micropower, uni-directional high-side and low-side current sense amplifier featuring a proprietary rail-to-rail input current sensing amplifier. The ISL28006 is ideal for high-side current sense applications where the sense voltage is usually much higher than the amplifier supply voltage. The device can be used to sense voltages as high as 28V when operating from a supply voltage as low as 2.7V. The micropower ISL28006 consumes only 50µA of supply current when operating from a 2.7V to 28V supply.
The ISL28006 features a common-mode input voltage range from 0V to 28V. The proprietary architecture extends the input voltage sensing range down to 0V, making it an excellent choice for low-side ground sensing applications. The benefit of this architecture is that a high degree of total output accuracy is maintained over the entire 0V to 28V common mode input voltage range.
The ISL28006 is available in fixed (100V/V, 50V/V, 20V/V and Adjustable) gains in the space saving 5 Ld SOT-23 package and the 6 Ld SOT-23 package for the adjustable gain part. The parts operate over the extended temperature range from -40°C to +125°C.
1. Please refer to TB347 for details on reel specifications.
2. These Intersil Pb-free plastic packaged products employ special Pb-free material sets, molding compounds/die attach materials, and 100% matte tin plate plus anneal (e3 termination finish, which is RoHS compliant and compatible with both SnPb and Pb-free soldering operations). Intersil Pb-free products are MSL classified at Pb-free peak reflow temperatures that meet or exceed the Pb-free requirements of IPC/JEDEC J STD-020.
3. For Moisture Sensitivity Level (MSL), please see device information page for ISL28006. For more information on MSL please see techbrief TB363.
4. The part marking is located on the bottom of the part.
Recommended Operating ConditionsAmbient Temperature Range (TA) . . . . . . . . . . . . . . . . . . .-40°C to +125°C
CAUTION: Do not operate at or near the maximum ratings listed for extended periods of time. Exposure to such conditions may adversely impact productreliability and result in failures not covered by warranty.
NOTES:
5. JA is measured with the component mounted on a high effective thermal conductivity test board in free air. See Tech Brief TB379 for details.
6. For JC, the “case temp” location is taken at the package top center.
Electrical Specifications VCC = 12V, VRS+ = 0V to 28V, VSENSE = 0V, RLOAD = 1MΩ, TA = +25°C unless otherwise specified.Boldface limits apply over the operating temperature range, -40°C to +125°C. Temperature data established by characterization.
ISC+ Short Circuit Sourcing Current VCC = VRS+ = 5V, RL = 10Ω 4.8 mA
ISC- Short Circuit Sinking Current VCC = VRS+ = 5V, RL = 10Ω 8.7 mA
Electrical Specifications VCC = 12V, VRS+ = 0V to 28V, VSENSE = 0V, RLOAD = 1MΩ, TA = +25°C unless otherwise specified.Boldface limits apply over the operating temperature range, -40°C to +125°C. Temperature data established by characterization. (Continued)
PARAMETER DESCRIPTION CONDITIONSMIN
(Note 7) TYPMAX
(Note 7) UNIT
FN6548 Rev 6.00 Page 5 of 26November 22, 2013
ISL28006
ICC Gain = 100 VRS+ > 2V, VSENSE = 5mV 50 59 µA
62 µA
Gain = 50, 20, VRS+ > 2V, VSENSE = 5mV 50 62 µA
63 µA
ADJ Gain = 21Rf = 100kΩ, Rg = 5kΩ
VRS+ > 2V, VSENSE = 5mV 50 62 µA
63 µA
VCC Supply Voltage Guaranteed by PSRR 2.7 28 V
Slew Rate Gain = 100 Pulse on RS+ pin, VOUT = 8VP-P (Figure 75) 0.58 0.76 V/µs
Gain = 50 Pulse on RS+ pin, VOUT = 8VP-P (Figure 75) 0.58 0.67 V/µs
Gain = 20 Pulse on RS+ pin, VOUT = 3.5VP-P (Figure 75) 0.50 0.67 V/µs
7. Compliance to datasheet limits is assured by one or more methods: production test, characterization and/or design.
8. DEFINITION OF TERMS:
• VSENSEA = VSENSE @ 100mV
• VSENSEB = VSENSE @ 20mV
• VOUTA = VOUT @ VSENSEA = 100mV
• VOUTB = VOUT @ VSENSEB = 20mV
• G =
9. VOS is extrapolated from the gain measurement.
10. % Gain Accuracy = GA =
11. Output Accuracy % VOA = , where VOUT = VSENSE X GAIN and VSENSE = 100mV
Electrical Specifications VCC = 12V, VRS+ = 0V to 28V, VSENSE = 0V, RLOAD = 1MΩ, TA = +25°C unless otherwise specified.Boldface limits apply over the operating temperature range, -40°C to +125°C. Temperature data established by characterization. (Continued)
FIGURE 71. ICC, VOS, VOA, CMRR, PSRR, GAIN ACCURACY FIGURE 72. INPUT BIAS CURRENT, LEAKAGE CURRENT
FIGURE 73. ts, SATURATION RECOVERY TIME FIGURE 74. GAIN vs FREQUENCY
FIGURE 75. SLEW RATE
RS+
VCC
RS-
VOUT
OUT
RLGND
VSENSE VRS+
1MΩ
+
-
+
-
ICC
RS+
VCC
RS-
VOUT
OUT
RLGND
VSENSEVRS+
1MΩ
+
-
+
-
R1
R2
VR1
VR2
RS+
VCC
RS-
VOUT
OUT
RL
GND
VRS-
VRS+
1MΩ
PULSE GENERATOR
RS+
VCC
RS-
VOUT
OUT
RL
GND
VSENSEVRS+
1MΩ
SIGNALGENERATOR
RS+
VCC
RS-
VOUT
OUT
RL
GNDVRS+
1MΩ
PULSEGENERATOR
FN6548 Rev 6.00 Page 18 of 26November 22, 2013
ISL28006
Applications Information
Functional DescriptionThe ISL28006-20, ISL28006-50 and ISL28006-100 are single supply, uni-directional current sense amplifiers with fixed gains of 20V/V, 50V/V and 100V/V respectively. The ISL28006-ADJ is single supply, uni-directional current sense amplifier with an adjustable gain via external resistors (see Figure 80). The ISL28006-ADJ is stable for gains of 20 and higher.
The ISL28006 is a 2-stage amplifier. Figure 76 shows the active circuitry for high-side current sense applications where the sense voltage is between 1.35V to 28V. Figure 77 shows the active circuitry for ground sense applications where the sense voltage is between 0V to 1.35V.
The first stage is a bi-level trans-conductance amp and level translator. The gm stage converts the low voltage drop (VSENSE) sensed across an external milli-ohm sense resistor, to a current (@ gm = 21.3µA/V). The trans-conductance amplifier forces a current through R1 resulting to a voltage drop across R1 that is equal to the sense voltage (VSENSE). The current through R1 is mirrored across R5 creating a ground-referenced voltage at the input of the second amplifier equal to VSENSE.
The second stage is responsible for the overall gain and frequency response performance of the device. The fixed gains (20, 50, 100) are set with internal resistors Rf and Rg. The variable gain (ADJ) has an additional FB pin and uses external
gain resistors to set the gain of the output. For the fixed gain amps the only external component needed is a current sense resistor (typically 0.001Ω to 0.01Ω, 1W to 2W).
The transfer function for the fixed gain parts is given in Equation 1.
The transfer function for the adjustable gain part is given in Equation 2.
Where ISRS is the product of the load current and the sense resistor and is equal to VSENSE.
When the sensed input voltage is >1.35V, the gmHI amplifier path is selected and the input gm stage derives its ~2.86µA supply current from the input source through the RS+ terminal. When the sense voltage at RS+ drops below the 1.35V threshold, the gmLO amplifier is enabled for Low Side current sensing. The gmLO input bias current reverses, flowing out of the RS- pin. Since the gmLO amplifier is sensing voltage around ground, it cannot source current to R5. A current mirror referenced off Vcc supplies the current to the second stage for generating a ground referenced output voltage. See Figures 69 and 70 for typical input bias currents for High and Low side current sensing.
VOUT GAIN ISRS VOS+ = (EQ. 1)
VOUT 1RFRG-------+
ISRS VOS+ = (EQ. 2)
FIGURE 76. HIGH-SIDE CURRENT DETECTION
RS+
RS-
gmHI
gmLO
RS
IS
+
-
LOAD
VSENSE
1.35V
IMIRROR
+
-OUT
Rf
Rg
R1
R5
VCC
HIGH-SIDESENSING
OPTIONALTRANSIENTPROTECTION
OPTIONALFILTERCAPACITOR
‘VSENSE
VCC = 2V to 28V
R2
R3
R4
I = 2.86µA
GND
VSENSE VRS+ = 2V TO 28V
FN6548 Rev 6.00 Page 19 of 26November 22, 2013
ISL28006
FIGURE 77. LOW-SIDE CURRENT DETECTION
RS-
gmHI
gmLO
RS
IS
+
-
LOAD
VSENSE
1.35V
+
-OUT
Rf
Rg
R1
R5
VCC
LOW-SIDESENSING
OPTIONALTRANSIENTPROTECTION
OPTIONALFILTERCAPACITOR
VSENSE
VCC = 2V TO 28V
R2
R3
R4
I = 2.86µA
VCC
GND
VSENSE VRS+= 0V TO 28V
RS+
IMIRROR
FN6548 Rev 6.00 Page 20 of 26November 22, 2013
ISL28006
Hysteretic ComparatorThe input trans-conductance amps are under control of a hysteretic comparator operating from the incoming source voltage on the RS+ pin (Figure 78). The comparator monitors the voltage on RS+ and switches the sense amplifier from the low-side gm amp to the high-side gm amplifier whenever the input voltage at RS+ increases above the 1.35V threshold. Conversely, a decreasing voltage on the RS+ pin, causes the hysteric comparator to switch from the high-side gm amp to the low-side gm amp as the voltage decreases below 1.35V. It is that low-side sense gm amplifier that gives the ISL28006 the proprietary ability to sense current all the way to 0V. Negative voltages on the RS+ or RS- are beyond the sensing voltage range of this amplifier.
Typical Application CircuitFigure 80 shows the basic application circuit and optional protection components for switched-load applications. For applications where the load and the power source is permanently connected, only an external sense resistor is needed. For applications where fast transients are caused by hot plugging the source or load, external protection components may be needed. The external current limiting resistor (RP) in Figure 80 may be required to limit the peak current through the internal ESD diodes to <20mA. This condition can occur in applications that experience high levels of in-rush current causing high peak voltages that can damage the internal ESD diodes. An RP resistor
value of 100Ω will provide protection for a 2V transient with the maximum of 20mA flowing through the input while adding only an additional 13µV (worse case over-temperature) of VOS. Refer to Equation 3:
Switching applications can generate voltage spikes that can overdrive the amplifier input and drive the output of the amplifier into the rails, resulting in a long overload recover time. Capacitors CM and CD filter the common mode and differential voltage spikes.
Error SourcesThere are 3 dominant error sources: gain error, input offset voltage error and Kelvin voltage error (see Figure 79). The gain error is dominated by the internal resistance matching tolerances. The remaining errors appear as sense voltage errors at the input to the amplifier. They are VOS of the amplifier and Kelvin voltage errors. If the transient protection resistor is added, an additional VOS error can result from the IxR voltage due to input bias current. The limiting resistor should only be added to the RS- input, due to the high-side gm amplifier (gmHI) sinking several micro amps of current through the RS+ pin.
Layout GuidelinesThe Kelvin Connected Sense ResistorThe source of Kelvin voltage errors is illustrated in Figure 79. The resistance of 1/2 Oz copper is ~1mΩ per square with a TC of ~3900ppm/°C (0.39%/°C). When you compare this unwanted parasitic resistance with the total 1mΩ to 10mΩ resistance of the sense resistor, it is easy to see why the sense connection must be chosen very carefully. For example, consider a maximum current of 20A through a 0.005Ωsense resistor, generating a VSENSE = 0.1 and a full scale output voltage of 10V (G = 100). Two side contacts of only 0.25 square per contact puts the VSENSE input about 0.5 x 1mΩ away from the resistor end capacitor. If only 10A the 20A total current flows through the kelvin path to the resistor, you get an error voltage of 10mV (10A x 0.5sq x 0.001Ω/sq. = 10mV) added to the 100mV sense voltage for a sense voltage error of 10% (0.110V-0.1)/0.1V) x 100.
FIGURE 78. GAIN ACCURACY vs VRS+ = 0V TO 2V
VRS+ (V)
-0.5
-0.4
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
0.4
0.5
0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0
AC
CU
RA
CY
(%
)
(EQ. 3)RP IRS- 100 130nA 13V= =
FIGURE 79. PC BOARD CURRENT SENSE KELVIN CONNECTION
PC Board
Non-uniformCurrent Flow
Current Sense Resistor1 to 10mO
Current In Current Out
Kelvin VS Contacts
Copper Trace30mO/Sq.
PC Board
Non-uniformCurrent Flow
Current Sense Resistor1 to 10mO
Current In Current Out
Kelvin VS Contacts
Copper Trace30mO/Sq.
CURRENT SENSE RESISTOR
1mΩ TO 10mΩ 1mΩ /SQ
CURRENT OUT CURRENT IN
NON-UNIFORMCURRENT FLOW
PC BOARD
KELVIN VS CONTACTS
1/2 Oz COPPER TRACE
FN6548 Rev 6.00 Page 21 of 26November 22, 2013
ISL28006
Overall Accuracy (VOA %)VOA is defined as the total output accuracy Referred-to-Output (RTO). The output accuracy contains all offset and gain errors, at a single output voltage. Equation 4 is used to calculate the % total output accuracy.
whereVOUT Actual = VSENSE x GAINExample: Gain = 100, For 100mV VSENSE input we measure 10.1V. The overall accuracy (VOA) is 1% as shown in Equation 5.
Power DissipationIt is possible to exceed the +150°C maximum junction temperatures under certain load and power supply conditions. It is therefore important to calculate the maximum junction temperature (TJMAX) for all applications to determine if power supply voltages, load conditions, or package type need to be modified to remain in the safe operating area. These parameters are related using Equation 6:
where:
• PDMAXTOTAL is the sum of the maximum power dissipation of each amplifier in the package (PDMAX)
• PDMAX for each amplifier can be calculated using Equation 7:
where:
• TMAX = Maximum ambient temperature
• JA = Thermal resistance of the package
• PDMAX = Maximum power dissipation of 1 amplifier
• VCC = Total supply voltage
• IqMAX = Maximum quiescent supply current of 1 amplifier
• VOUTMAX = Maximum output voltage swing of the application
Revision HistoryThe revision history provided is for informational purposes only and is believed to be accurate, but not warranted. Please go to web to make sure you have the latest Rev.
DATE REVISION CHANGE
November 22, 2013 FN6548.6 Added eight new Typical Performance Curves1. Av=100 Capacitive Load Drive Gain vs Freq2. Av=100 Capacitive Load Drive Phase vs Freq3. Av=50 Capacitive Load Drive Gain vs Freq4. Av=50 Capacitive Load Drive Phase vs Freq5. Av=20 Capacitive Load Drive Gain vs Freq6. Av=20 Capacitive Load Drive Phase vs Freq7. High Side Operation Input Bias Currents8. Low Side Operation Input Bias Currents
Under Electrical Specifications Table:Changed parameter from Is to Icc to clarify supply currentOrdering information table on page 3: Changed Note 4 location in the table.
April 12, 2011 FN6548.5 Converted to new templatePage 1 - Changed headings for “Typical Application” and “Gain Accuracy vs VRS+ = 0V to 28V” to Figure titles (Figures 1 and 2).Page 1 - Updated Intersil Trademark statement at bottom of page 1 per directive from Legal.Page 7 - Updated over temp note in Min Max column of spec tables from "Parameters with MIN and/or MAX limits are 100% tested at +25°C, unless otherwise specified. Temperature limits established by characterization and are not production tested." to new standard "Compliance to datasheet limits is assured by one or more methods: production test, characterization and/or design." Page 19 - Figure 69, Low side current detection schematic: Moved the LOAD from the ground side of the power side circuit to the high side.
September 2, 2010 FN6548.4 Added -T7A tape and reel options to Ordering Information Table for all packages.
May 12, 2010 FN6548.3 Added Note 4 to Part Marking Column in “Ordering Information” on page 3.Corrected hyperlinks in Notes 1 and 3 in “Ordering Information” on page 3.
April 8, 2010 Removed “Coming Soon” from evaluation boards in “Ordering Information” on page 3.
April 7, 2010 Added “Related Literature” on page 1Updated Package Drawing Number in the “Ordering Information” on page 3 for the 20V, 50V and 100V options from MDP0038 to P50.64A.Revised package outline drawing from MDP0038 to P5.064A on page 24. MDP0038 package contained 2 packages for both the 5 and 6 Ld SOT-23. MDP0038 was obsoleted and the packages were separated and made into 2 separate package outline drawings; P5.064A and P6.064A. Changes to the 5 Ld SOT-23 were to move dimensions from table onto drawing, add land pattern and add JEDEC reference number.
March 10, 2010 FN6548.2 Releasing adjustable gain option.Added adjustable block diagram (Page 2), Added adjustable gain limits to electrical spec table, added Figures 47 through 60, Added +85°C curves to Figures 6 thru 14, 20 thru 28, 34 thru 42, and Figures 48 thru 56. Modified Figure 70.
February 4, 2010 FN6548.1 -Page 1:Edited last sentence of paragraph 2.Moved order of GAIN listings from 20, 50, 100 to 100, 50, 20 in the 3rd paragraph.Under Features ....removed "Low Input Offset Voltage 250µV, max"Under Features .... moved order of parts listing from 20, 50, 100 (from top to bottom) to 100, 50, 20.-Page 3: Removed coming soon on ISL28006FH50Z and ISL28006FH20Z and changes the order or listing them to 100, 50, 20.-Page 5: VOA test. Under conditions column ...deleted 20mV to. It now reads ... Vsense = 100mV SR test. Under conditions column ..deleted what was there. It now reads ... Pulse on RS+pin, See Figure 51-Page 6: ts test. Removed Gain = 100 and Gain = 100V/V in both description and conditions columns respectively.-Page 9: Added VRS+= 12V to Figures 16, 17, 18. -Page 11: Added VRS+= 12V to Figures 30, 31, 32. -Page 13 & 14: Added VRS+= 12V to Figures 44, 45, 46. -Page 14 Added Figure 51 and adjusted figure numbers to account for the added figure.-Figs 8, 26, and 40 change "HIGH SIDE" to "VRS = 12V", where RS is subscript.-Figs 9, 27, and 41 change "LOW SIDE" to "VRS = 0.1V", where RS is subscript.
December 14, 2009 FN6548.0 Initial Release
FN6548 Rev 6.00 Page 23 of 26November 22, 2013
ISL28006
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